Purchased this as a set with the Arcturus Auto Rear Light. I love the fact that I can enable the auto on/off feature and the brightness levels are excellent. The fact that I can rotate position as well as replace the battery in future makes this a very good choice for a light. Excellent battery life as I have been using it for the past 3-4 days for a few hours a day without any need to recharge. Have yet to try in darker conditions but am not concerned at this point and time.